LB7: wheel speed sensor's

d-max joe

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Feb 6, 2009
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baltimore,md
all of them are bad according to tech 2..front both and rear sensor. guy said burnouts could do the back one but i was wondering if it is showing casue my tires are 33inch? and it doesnt know that i changed tires size. i sold ppe like two monthas ago and now have problems any body have same problem or herd of this?
 

JoshH

Daggum farm truck
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Is your speedometer working and your transmission shifting ok?
 

d-max joe

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Feb 6, 2009
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=no issuses while ppe was in bout months 1/2 ago now sense then i been having prob. with the brakes having this feeling to them and now wheel speed sensors say bad. i cant get over all them being back the guy said they were out of sync with each other from burnouts?? is that true?
 

05' Ditry Duramax

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May 3, 2008
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Try and describe the "feeling" you get in the brakes a little more. Maybe that's related. I've wouldn't think a bunch of burnouts will take out a sensor. I know they will take out the G80 though.
 
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d-max joe

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Feb 6, 2009
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yeah thats true but the feeling is when i step on it like there is a car pulled out n i had to jam on them it would kick back for a sec then apply.
 

coker6303

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Aug 6, 2009
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I know that if the speed setting between the ECM and TCM are not pretty close together the ABS brakes will be screwy. Such as when you hit the brakes to stop the pedal will shudder and feel really soft before it actually applies brake pressure to the pads. Can be a wake up call if it happens. ;)
 

TIM Z

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Jan 17, 2009
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I had this problem on a 2002 Tahoe.

Corrosion gets underneath the wheel sensor, forcing it up and it cant read correctly.

Be careful as you prob need to pull them out, clean out the hole/surface they read, reinstall them and put a good layer of silcone over top of them to keep condensation out.

A little grease on them before popping them back in helps too.
 

BlackOpsDiesel

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Nov 20, 2009
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i didnt feel like dealing with the sensors anymore since I always check my tire pressure.... so I just didnt put them in the new wheels on my chubby... only problem is I have that damn light on that is on the dash...
 

heymccall

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Aug 24, 2009
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If the speedo is working, transmission shifts normal, and the ABS lamp is off, the rear speed sensor is fine.

If the ABS lamp is off and the brakes have a skipping feeling when slowing from 8 to 3mph, then corrosion has lifted one or both front wheel speed sensors out of place (or a front wheel bearing is worn out). If the front sensors were bad, the ABS lamp would be illuminated (broken wire or broken sensor).

As for the tire size change, again an ABS lamp would be illuminated and a fault code stored. And the lamp wouldn't illuminate at startup, but rather after reaching 20 mph or so.

With the front wheels off the ground, key off, grab the top and bottom of each tire and rock in and out. Movement=bad wheel bearing assy (which will also give the brakes a skipping feeling, again while slowing between 8 and 3mph). No movement= proceed to unplug each wheel speed sensor and connect a multimeter set on ACmv. Hand spin each wheel. Each side will generate a small AC voltage. Whichever side is least consistent will be the problem side.

Remove the caliper ear assy and rotor on that side, and remove the allen screw for that sensor. Then proceed to read this http://www.carquest.com/common/downloads/partsTechBrakeCQB 02-02.pdf

If the sensor does not pull out easily, it has a growth of corrosion grabbing the O-ring. The only solution in this case is to replace the sensor (once forcibly removed) with a new one.


And lastly, find a new mechanic, or at least teach him how to use a Tech II. And do all the burnouts you feel like doing, BECAUSE your problem is unrelated.
 
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d-max joe

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Feb 6, 2009
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baltimore,md
ok thanks and yea he needs some teaching on that thing lol but i dont think the rear sensor is bad then n the fronts ill check tommorow n post a update